TY - JOUR

T1 - Measurements of long-range azimuthal anisotropies and associated Fourier coefficients for pp collisions at √s = 5.02 and 13 TeV and p + Pb collisions at √sNN = 5.02 TeV with the ATLAS detector

AU - Barton, Adam Edward

AU - Beattie, Michael

AU - Bertram, Iain Alexander

AU - Borissov, Guennadi

AU - Bouhova-Thacker, Evelina Vassileva

AU - Dearnaley, William

AU - Fox, Harald

AU - Grimm, Kathryn Ann Tschann

AU - Henderson, Robert Charles William

AU - Hughes, Gareth

AU - Jones, Roger William Lewis

AU - Kartvelishvili, Vakhtang

AU - Long, Robin Eamonn

AU - Love, Peter Allan

AU - Muenstermann, Daniel Matthias Alfred

AU - Parker, Adam Jackson

AU - Skinner, Malcolm

AU - Smizanska, Maria

AU - Walder, James William

AU - Wharton, Andy

AU - The ATLAS collaboration

PY - 2017/8/22

Y1 - 2017/8/22

N2 - ATLAS measurements of two-particle correlations are presented for √s =5.02 and 13 TeV pp collisions and for √sNN =5.02 TeV p+Pb collisions at the LHC. The correlation functions are measured as a function of relative azimuthal angle Δϕ, and pseudorapidity separation Δη, using charged particles detected within the pseudorapidity interval |η|<2.5. Azimuthal modulation in the long-range component of the correlation function, with |Δη|>2, is studied using a template fitting procedure to remove a “back-to-back” contribution to the correlation function that primarily arises from hard-scattering processes. In addition to the elliptic, cos(2Δϕ), modulation observed in a previous measurement, the pp correlation functions exhibit significant cos(3Δϕ) and cos(4Δϕ) modulation. The Fourier coefficients vn,n associated with the cos(nΔϕ) modulation of the correlation functions for n=2–4 are measured as a function of charged-particle multiplicity and charged-particle transverse momentum. The Fourier coefficients are observed to be compatible with cos(nϕ) modulation of per-event single-particle azimuthal angle distributions. The single-particle Fourier coefficients vn are measured as a function of charged-particle multiplicity, and charged-particle transverse momentum for n=2–4. The integrated luminosities used in this analysis are, 64 nb−1 for the √s =13 TeV pp data, 170 nb−1 for the √s =5.02 TeV pp data, and 28 nb−1 for the √sNN =5.02 TeV p+Pb data.

AB - ATLAS measurements of two-particle correlations are presented for √s =5.02 and 13 TeV pp collisions and for √sNN =5.02 TeV p+Pb collisions at the LHC. The correlation functions are measured as a function of relative azimuthal angle Δϕ, and pseudorapidity separation Δη, using charged particles detected within the pseudorapidity interval |η|<2.5. Azimuthal modulation in the long-range component of the correlation function, with |Δη|>2, is studied using a template fitting procedure to remove a “back-to-back” contribution to the correlation function that primarily arises from hard-scattering processes. In addition to the elliptic, cos(2Δϕ), modulation observed in a previous measurement, the pp correlation functions exhibit significant cos(3Δϕ) and cos(4Δϕ) modulation. The Fourier coefficients vn,n associated with the cos(nΔϕ) modulation of the correlation functions for n=2–4 are measured as a function of charged-particle multiplicity and charged-particle transverse momentum. The Fourier coefficients are observed to be compatible with cos(nϕ) modulation of per-event single-particle azimuthal angle distributions. The single-particle Fourier coefficients vn are measured as a function of charged-particle multiplicity, and charged-particle transverse momentum for n=2–4. The integrated luminosities used in this analysis are, 64 nb−1 for the √s =13 TeV pp data, 170 nb−1 for the √s =5.02 TeV pp data, and 28 nb−1 for the √sNN =5.02 TeV p+Pb data.

U2 - 10.1103/PhysRevC.96.024908

DO - 10.1103/PhysRevC.96.024908

M3 - Journal article

VL - 96

JO - Physical Review C

JF - Physical Review C

SN - 0556-2813

IS - 2

M1 - 024908

ER -